/Engine/Plugins/Online/OnlineSubsystemUtils/Source/OnlineSubsystemUtils/Public/VoiceInterfaceImpl.h
Does a given id exist in the system wide mute list
true if the net id is on the system wide mute list, false otherwise
virtual bool IsSystemWideMuted ( const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & UniqueId ) const